Device for ventilation systems in spaces

ABSTRACT

A device in a ventilation system for spaces and comprising a channel for admitted air opening into said spaces and housing a throttling member occupying at least almost the entire crosssectional area of the channel and composed of mutually parallel thin layers subdividing said throttling member into a great number of tubular straight passages with a so small diameter as effectively to counteract occurrance of disturbing noise.

United States Patent 1191 Christiansen Feb. 6, 1973 1541 DEVICE FOR VENTILATION SYSTEMS 3,492,934 2/1970 Steigerwald ..98/33 R IN SPACES 2,161,027 6/1939 Dollinger ..181/46 2,750,865 6/1956 Tutt ...98/40B [75] chrlst'ansen Bandhagen 3,071,160 1/1963 Weichbrod... ..138/40 Swede 2,950,776 8/1960 Stephens ..181/46 x [73] Assignee: Carl George Munters, Stocksund,

Sweden Primary ExaminerWilliam E. Wayner Filed: J y 1970 Attorney-Sol B. W1czer Appl. No.: 51,620

Foreign Application Priority Data July 11, 1969 Sweden ..9910/69 US. Cl ..98/40 I), 138/40, 181/40 Int. Cl. ..F24f 13/06 Field of Search ..181/46; 98/40, 40 D, 40 B, 98/37, 32; 138/44, 40, 39

[56] References Cited UNITED STATES PATENTS 2,291,220 7/1942 Germonprez ..98/40 D X A device in a ventilation system for spaces and comprising a channel for admitted air opening into said spaces and housing a throttling member occupying at least almost the entire cross-sectional area of the channel and composed of mutually parallel thin layers subdividing said throttling member into a great number of tubular straight passages with a so small diameter as effectively to counteract occurrance of disturbing noise.

ABSTRACT 7 Claims, 2 Drawing Figures DEVICE FOR VENTILATION SYSTEMS IN SPACES BACKGROUND OF THE INVENTION This invention relates to a ventilation system for spaces or rooms in office buildings, dwelling houses, factories etc. which system comprises channels for air which is advanced through the channels by means of a fan and which opens into the spaces.

In a ventilation system which comprises a plurality of channels for introduction of fresh or warm air, here commonly called admitted air, into spaces or rooms, throttling members are used which have to their purpose to ensure the desired distribution of the air or to produce such pressure drops that, viewed from the viewpoint of fire prevention, a spreading of flue gases or the like from one space to another in case of a fire is impeded.

In practice the throttling member is mostly formed as a flap which has the drawback that it at least in certain throttling positions produces hissing or whistling noises which can be very disturbing.

SUMMARY OF THE INVENTION Over this prior art the present invention is characterized by provision in the channel of a throttling member composed of a laminate of parallel thin layers subdividing the member into a great number of tubular straight passages having a hydraulic diameter less than 3 millimeters in order to counteract production of disturbing noise, said throttling member having such an area transverse to the longitudinal direction of the passages as at least approximately to occupy the entire cross-sectional area of the channel. The throttling effect is based on the property of the throttling mem'ber embodying the main feature of the invention that the flow of air through the fine channels becomes a laminar one with a high coefficient of friction. According to the invention there is a minor quantity of air per each passage and unit of time than in the known structure where the throttling member is disposed in a portion of the ventilation channel with a restricted passage area. By this novel arrangement the important effect is gained that deposition of dust and other solid particles, as a consequence of the small cross-section of each individual passage, can be allowed to continue during a longer period of time than washitherto possible with fear of any disturbing clogging. As the active area of throughflow of the throttling member is not adjustable as to correspond to a specific desired pressure drop, said member is instead adjusted by control of the length of the member itself and therewith of the passages formed therein. The noise produced in the throttling member produced by the member itself is very insignificant and vthus, negligible, when compared with other noises occurring or generated in the channel.

THE DRAWINGS The invention is described in more detail with reference to an embodiment shown by way of example in the accompanying drawing which forms part of this specification, other characterizing features, objects and advantages of the invention being indicated. In the drawings,

FIG. 1 is a vertical sectional view of a portion of a ceiling with a ventilation system formed in accordance with the invention mounted therein, and

FIG. 2 is a sectional view on a larger scale taken on the line lI-Il of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawing, reference numeral 1 denotes a portion of the structural ceiling of a room.

Said ceiling may be made of concrete. At a minor distance below said ceiling there is provided a suspended ceiling 12. A ventilation system constructed according to the invention is positioned in the interspace between said ceilings. The ventilation system comprises at least one horizontal main duct 14 which is in engagement with a pressure fan and from which a plurality of vertical branch ducts 16 extend to open into the room or rooms. An opening 18 in the suspended ceiling l2 fits to the duct 16. An intake member 20 has a tubular socket 22 fitting to the crosssection of the opening portion of the duct 16 and at the same time covers the opening 18. The intake member 20 may in known manner be composed of a plurality of conical, concentrically disposed hoppers which by means of a central tap 24 are connected with a crossmember 26 anchored in the tubular socket 22. The intake member 20 has for its purpose uniformly to distribute the intake air laterally. After unscrewing of the pin 24 the individual conical hoppers can be removed for cleaning.

According to the invention there is inserted into the suitably cylindrical socket 22 a throttling member 28 which is sealed against said socket by means of a pair of sealing rings 30 made of rubber, for example.

The throttling member is preferably composed of alternating plane strips 32 and corrugated strips 34 as will be seen from FIG. 2. The strips are suitably made of a non-combustible material such as thin sheet or foil material of asbestos or metal having a thickness of at the utmost some few tenths of a millimeter down to fractions of a tenth of one millimeter. The member 28 is suitably manufactured in such a manner that one plane and one corrugated strip are initially combined with one another to an one-face corrugated structure which then is wound up helically to constitute a disc having a diameter which more or less exactly corresponds with the interior diameter of the tubular socket 22. If the strips are of asbestos or other fibrous material they may be provided with a stiffening impregnation or coating by a reinforcing substance in a manner known per se. This reinforcing substance may, if desired, be located only along the edge portions of the disc-shaped member 28 and at the same time ensure coherence of the strips with one another. According to the invention the spacing between the plane strips 32 is of the order of magnitude of 3 mms or less, such as 1.5 mms. In this way a very great number of tubular straight passages 36 is produced, the longitudinal delayed to a substantial degree so that the member remains operative during a very long period of time. Due to the fact that it is mounted by insertion into the tubular socket 22 which is easy removable, a cleaning can be effected at suitable intervals or the throttling member be replaced.

The tendency of the dust particles to deposit at the air intake into the passages 36 is much reduced by the insignificant thickness of the strips 32, 34 which firstly counteracts occurrence of turbulence at the intake and secondly does not form any edge surface area on which the particles could deposit. Since the passages 36 in the throttling members or discs 28 are straight also for the continued flow ofthe air within same, deposit of dust is counteracted on the interior walls of the passages also an effect to which the laminar flow through the passages contributes also.

The throttling member 28 according to the invention further brings about an alignment of the air stream if this e.g. by changes in direction during the passage from the duct 14 to the duct 16 is imparted a distorted distribution of velocity. Thus, also that distorting effect is avoided which the known flaps have when they take throttling position.

Since the throttling means 28 is stationary and its active passage area can not be varied, a desired throttling grade is achieved eg by having throttling members of different lengths kept in stock which at the same air velocity result in different pressure drops, if desired according a predetermined modular system. The throttling grade may be 3 to up to 20 to 30 mms H O. It is also possible to combine several discshaped throttling members each having the same thickness, i.e. length of the passages 36, so as in response to requirement position the members in a series one behind the other to a number corresponding to the desired pressure drop.

in order to avoid as much as possible deposition of solid substances on the throttling member 28, the entering air ought to be filtered. A filter 38 is indicated in conduit 14. This filter is mounted centrally and thus suitably common for a plurality of throttling units 28.

The layers or strips in the throttling member may be .given honeycomb structure. As a measure unit for the cross-section of the passages in the throttling member the hydraulic diameter is used as is evident from the values given above for this diameter. Under such conditions of operation where especially high demands on quiet function are set up and at the same time a high velocity of the air is desired, it has proved tobe advantageous to make the layers or strips of a fibrous material which cannot be brought to vibration by the air stream and thereby produce disturbing noise.

While one more or less specific embodiment of the invention has been shown and described, it is to be understood that this is for purpose of illustration only, and that the invention is not to be limited thereby, but its scope is to be determined by the appended claims.

What is claimed is:

l. A ventilation system comprising a duct opening into a space, a throttling member in said duct mounted near said opening and extending across the entire cross-sectional area of said duct for reducing noisy air passage passing from said duct to said space, said throttling member comprising a cellular laminate of mutually parallel thin layers, each layer havin a thickness of from a few tenths down to fractions 0 a tenth of a millimeter, said layers sub-dividing said throttling member into straight tubular air passageways extending from end to end of said member, whereby air passing through said duct is sub-divided to pass through the numerous tubular passageways each having a diameter less than about three millimeters, and a length in the direction of the air passage greatly exceeding said diameter.

2. The device as defined in claim 1 wherein the tubular passageways of said throttling member have a diameter in the range of less than about 1' h millimeters up to about three millimeters and a total length exceeding about 50 millimeters.

3. The device as defined in claim 1 wherein said tubular throttling members may be formed of variable sizes having a total length in the range of about 50 to 200 millimeters.

4. The device as defined in claim 3 wherein said throttling member is formed of several members arranged in a series with its tubular passageways aligned and having a total length in the range of 50 to 200 millimeters.

5. The device as defined in claim l wherein said throttling member is formed of fibrous corrugated sheets formed into a laminated body, the corrugations comprising said tubular passageways.

6. The device as defined in claim 1 including a space intake member mounted at the opening of said duct with said space, said throttling member being placed sufficiently close to said intake member to supply air evenly distributed in laminar flow to said intake member. a I

7. The device as defined in claim 6 wherein'said intake member and said throttling member are combined as a unit insertable into and removable from said duct. 

1. A ventilation system comprising a duct opening into a space, a throttling member in said duct mounted near said opening and extending across the entire cross-sectional area of said duct for reducing noisy air passage passing from said duct to said space, said throttling member comprising a cellular laminate of mutually parallel thin layers, each layer having a thickness of from a few tenths down to fractions of a tenth of a millimeter, said layers sub-dividing said throttling member into straight tubular air passageways extending from end to end of said member, whereby air passing through said duct is sub-divided to pass through the numerous tubular passageways each having a diameter less than about three millimeters, and a length in the direction of the air passage greatly exceeding said diameter.
 1. A ventilation system comprising a duct opening into a space, a throttling member in said duct mounted near said opening and extending across the entire cross-sectional area of said duct for reducing noisy air passage passing from said duct to said space, said throttling member comprising a cellular laminate of mutually parallel thin layers, each layer having a thickness of from a few tenths down to fractions of a tenth of a millimeter, said layers sub-dividing said throttling member into straight tubular air passageways extending from end to end of said member, whereby air passing through said duct is sub-divided to pass through the numerous tubular passageways each having a diameter less than about three millimeters, and a length in the direction of the air passage greatly exceeding said diameter.
 2. The device as defined in claim 1 wherein the tubular passageways of said throttling member have a diameter in the range of less than about 1 1/2 millimeters up to about three millimeters and a total length exceeding about 50 millimeters.
 3. The device as defined in claim 1 wherein said tubular throttling members may be formed of variable sizes having a total length in the range of about 50 to 200 millimeters.
 4. The device as defined in claim 3 wherein said throttling member is formed of severAl members arranged in a series with its tubular passageways aligned and having a total length in the range of 50 to 200 millimeters.
 5. The device as defined in claim 1 wherein said throttling member is formed of fibrous corrugated sheets formed into a laminated body, the corrugations comprising said tubular passageways.
 6. The device as defined in claim 1 including a space intake member mounted at the opening of said duct with said space, said throttling member being placed sufficiently close to said intake member to supply air evenly distributed in laminar flow to said intake member. 